1. Field of the Invention
The present invention relates generally to electronic imaging systems such as digital cameras. In particular, the present invention relates to systems and methods for providing the user with information as to the portion of an image that is in focus.
2. Description of the Related Art
During the recent past, camera technology has greatly improved. A variety of still cameras are presently commercially available that include such features as an "automatic" focus lens. Such cameras with the automatic focus feature, automatically gather focusing information and adjust the lens of the camera to bring the image received by the camera at the moment the picture is taken into focus. Conventionally, such auto-focus cameras selected predetermined areas in the image to be captured as points that must be in focus. With such cameras, the user is generally not able to view the image through the lens that will gather the image for exposure to the film. Instead, the user views the image or scene through a false lens that is built into the housing of the camera. The scene framed by the false lens generally approximates the image that will be captured on film when the picture is taken. However, a particular problem with such auto-focus cameras is that they do not provide the user with any feedback or information as to the portions of the image that will be in focus when the picture is taken. Since the image is viewed through a false lens, the user must hope the portion of the image of importance is in focus when the picture is taken or hope that the portion of the image of importance falls within an area used by the auto focus mechanism.
Even with cameras that allow the user to view the image to be captured through the current settings of the actual lens, such as a single lens reflex (SLR) camera or a digital camera with a live view finder, identifying the portions of the image that are in focus can be particularly problematic. The image to be captured is typically displayed in a view finder with the image significantly reduced in size. Moreover, the resolution and picture quality of such view finders is very poor. Therefore, when viewing an image to be photographed or captured it is very difficult to identify the portions of the image that are in focus. Because of the poor resolution and small size of the images, in many instances it is not possible to determine the portions of the image that are in focus. This problem is even more significant for digital cameras since ideally, the user will view the image through the view finder for only a few seconds before deciding whether to take the picture, change the view or adjust the focus. Moreover, in the normal use of such cameras, it is very difficult for the user to determine the portion of the image that is in focus, especially when under pressure of the moment to get a picture. It is very common for users, even with SLR and digital cameras, to get out of focus pictures. Thus, there is need for a system that alerts the user as to the portion of the image that is in focus.
A variety of video cameras for capturing moving pictures of live scenes have been developed and their use is now widespread. Many existing video cameras provide for both the manual and the automatic focusing on images being filmed. Like digital cameras, video cameras typically provide a live view finder. These view finders are also very small, usually less than one square inch. They also suffer from the shortcoming of providing little feedback to the user as to what portions of the scene being filmed are in focus and what portions are not in focus. Therefore, it is very difficult for the user to determine whether an image is satisfactorily in focus using the auto focus mechanisms of the video camera or whether the user should resort to manual adjustment to focus in on the portions of the image as desired. In many instances, the user must view the scene for a significant period of time to ensure that the objects of interest in the scene are in focus. For live action filming, this is a particular problem because the user is not able to quickly adjust the focus as desired to film objects in the scene of interest.
Therefore, there is a need for a system and method for providing the user with feedback as to the portions of an image that will be in focus when the picture is taken. In particular, there is a need for a system and method that displays in a visually distinct manner the portions of an image that are in focus so that they can be readily and quickly identified by the user.